Functional Description

02068-DSH-001-C

Mindspeed Technologies

®

8

Mindspeed Proprietary and Confidential

3.4

Mean Power Control Loop

To maintain constant average optical power, the CX02068 incorporates a control loop to compensate for the

changes in laser threshold current over temperature and lifetime. A monitor photodiode mounted in the laser

package is used to convert the optical power into a photocurrent. The MPC loop adjusts the laser bias current so

Safety logic is provided in order to limit the maximum bias current. The bias current at which the safety logic trips

flag OCA is asserted LOW. A loop failure alarm is also provided to detect when the bias current can no longer be

adjusted to achieve the desired average optical power.

Figure 3-3.

Figure 3-4.

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